NAMED.CONF(5) BSD Programmer's Manual NAMED.CONF(5) NNAAMMEE nnaammeedd..ccoonnff - configuration file for named(8) OOVVEERRVVIIEEWW BIND 8 is much more configurable than previous release of BIND. There are entirely new areas of configuration, such as access control lists and categorized logging. Many options that previously applied to all zones can now be used selectively. These features, plus a consideration of fu- ture configuration needs led to the creation of a new configuration file format. GGeenneerraall SSyynnttaaxx A BIND 8 configuration consists of two general features, statements and comments. All statements end with a semicolon. Many statements can con- tain substatements, which are each also terminated with a semicolon. The following statements are supported: llooggggiinngg specifies what the server logs, and where the log messages are sent ooppttiioonnss controls global server configuration options and sets defaults for oth- er statements zzoonnee defines a zone aaccll defines a named IP address matching list, for access control and other uses kkeeyy specifies key information for use in authentication and authorization ttrruusstteedd--kkeeyyss defines DNSSEC keys that are preconfigured into the server and implic- itly trusted sseerrvveerr sets certain configuration options for individual remote servers ccoonnttrroollss declares control channels to be used by the nnddcc utility iinncclluuddee includes another file The llooggggiinngg and ooppttiioonnss statements may only occur once per configuration, while the rest may appear numerous times. Further detail on each state- ment is provided in individual sections below. Comments may appear anywhere that whitespace may appear in a BIND config- uration file. To appeal to programmers of all kinds, they can be written in C, C++, or shell/perl constructs. C-style comments start with the two characters /* (slash, star) and end with */ (star, slash). Because they are completely delimited with these characters, they can be used to comment only a portion of a line or to span multiple lines. C-style comments cannot be nested. For example, the following is not valid because the entire comment ends with the first */: /* This is the start of a comment. This is still part of the comment. /* This is an incorrect attempt at nesting a comment. */ This is no longer in any comment. */ C++-style comments start with the two characters // (slash, slash) and continue to the end of the physical line. They cannot be continued across multiple physical lines; to have one logical comment span multiple lines, each line must use the // pair. For example: // This is the start of a comment. The next line // is a new comment, even though it is logically // part of the previous comment. Shell-style (or perl-style, if you prefer) comments start with the char- acter # (hash or pound or number or octothorpe or whatever) and continue to the end of the physical line, like C++ comments. For example: # This is the start of a comment. The next line # is a new comment, even though it is logically # part of the previous comment. _W_A_R_N_I_N_G_: you cannot use the ; (semicolon) character to start a comment such as you would in a zone file. The semicolon indicates the end of a configuration statement, so whatever follows it will be interpreted as the start of the next statement. CCoonnvveerrttiinngg ffrroomm BBIINNDD 44..99..xx BIND 4.9.x configuration files can be converted to the new format by us- ing _s_r_c_/_b_i_n_/_n_a_m_e_d_/_n_a_m_e_d_-_b_o_o_t_c_o_n_f, a shell script that is part of the BIND 8.2.x source kit. DDOOCCUUMMEENNTTAATTIIOONN DDEEFFIINNIITTIIOONNSS Described below are elements used throughout the BIND configuration file documentation. Elements which are only associated with one statement are described only in the section describing that statement. _a_c_l___n_a_m_e The name of an _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t as defined by the aaccll statement. _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t A list of one or more _i_p___a_d_d_r, _i_p___p_r_e_f_i_x, _k_e_y___i_d, or _a_c_l___n_a_m_e elements, as described in the _A_D_D_R_E_S_S _M_A_T_C_H _L_I_S_T_S section. _d_o_t_t_e_d_-_d_e_c_i_m_a_l One or more integers valued 0 through 255 separated only by dots (``.''), such as 123, 45.67 or 89.123.45.67. _d_o_m_a_i_n___n_a_m_e A quoted string which will be used as a DNS name, for example "my.test.domain". _p_a_t_h___n_a_m_e A quoted string which will be used as a pathname, such as "zones/master/my.test.domain". _i_p___a_d_d_r An IP address in with exactly four elements in _d_o_t_t_e_d_-_d_e_c_i_m_a_l notation. _i_p___p_o_r_t An IP port _n_u_m_b_e_r. _n_u_m_b_e_r _i_s _l_i_m_i_t_e_d _t_o 0 through 65535, with values below 1024 typically restricted to root-owned processes. In some cases an asterisk (``*'') character can be used as a placeholder to select a random high-numbered port. _i_p___p_r_e_f_i_x An IP network specified in _d_o_t_t_e_d_-_d_e_c_i_m_a_l form, followed by ``/'' and then the number of bits in the netmask. E.g. 127/8 is the network 127.0.0.0 with netmask 255.0.0.0. 1.2.3.0/28 is network 1.2.3.0 with netmask 255.255.255.240. _k_e_y___n_a_m_e A string representing the name of a shared key, to be used for transac- tion security. _n_u_m_b_e_r A non-negative integer with an entire range limited by the range of a C language signed integer (2,147,483,647 on a machine with 32 bit inte- gers). Its acceptable value might further be limited by the context in which it is used. _s_i_z_e___s_p_e_c A _n_u_m_b_e_r, the word unlimited, or the word default. The maximum value of _s_i_z_e___s_p_e_c is that of unsigned long integers on the machine. unlimited requests unlimited use, or the maximum available amount. default uses the limit that was in force when the server was started. A _n_u_m_b_e_r can optionally be followed by a scaling factor: K or k for kilobytes, M or m for megabytes, and G or g for gigabytes, which scale by 1024, 1024*1024, and 1024*1024*1024 respectively. Integer storage overflow is currently silently ignored during conver- sion of scaled values, resulting in values less than intended, possibly even negative. Using unlimited is the best way to safely set a really large number. _y_e_s___o_r___n_o Either yes or no. The words true and false are also accepted, as are the numbers 1 and 0. AADDDDRREESSSS MMAATTCCHH LLIISSTTSS SSyynnttaaxx _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t = 1*_a_d_d_r_e_s_s___m_a_t_c_h___e_l_e_m_e_n_t _a_d_d_r_e_s_s___m_a_t_c_h___e_l_e_m_e_n_t = [ "!" ] ( _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t / _i_p___a_d_d_r_e_s_s / _i_p___p_r_e_f_i_x / _a_c_l___n_a_m_e / "key " _k_e_y___i_d ) ";" DDeeffiinniittiioonn aanndd UUssaaggee Address match lists are primarily used to determine access control for various server operations. They are also used to define priorities for querying other nameservers and to set the addresses on which nnaammeedd will listen for queries. The elements which constitute an address match list can be any of the following: ++oo an _i_p_-_a_d_d_r_e_s_s (in _d_o_t_t_e_d_-_d_e_c_i_m_a_l notation, ++oo an _i_p_-_p_r_e_f_i_x (in the '/'-notation), ++oo A _k_e_y___i_d, as defined by the kkeeyy statement, ++oo the name of an address match list previously defined with the aaccll statement, or ++oo another _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t. Elements can be negated with a leading exclamation mark (``!''), and the match list names any, none, localhost and localnets are predefined. More information on those names can be found in the description of the aaccll statement. The addition of the kkeeyy clause made the name of this syntactic element something of a misnomer, since security keys can be used to validate ac- cess without regard to a host or network address. Nonetheless, the term ``address match list'' is still used throughout the documentation. When a given IP address or prefix is compared to an address match list, the list is traversed in order until an element matches. The interpreta- tion of a match depends on whether the list is being used for access con- trol, defining lliisstteenn--oonn ports, or as a topology, and whether the element was negated. When used as an access control list, a non-negated match allows access and a negated match denies access. If there is no match at all in the list, access is denied. The clauses aallllooww--qquueerryy, aallllooww--ttrraannssffeerr, aallllooww-- uuppddaattee, aallllooww--rreeccuurrssiioonn, and bbllaacckkhhoollee all use address match lists like this. Similarly, the lliisstteenn--oonn option will cause the server to not ac- cept queries on any of the machine's addresses which do not match the list. When used with the ttooppoollooggyy option, a non-negated match returns a dis- tance based on its position on the list (the closer the match is to the start of the list, the shorter the distance is between it and the serv- er). A negated match will be assigned the maximum distance from the server. If there is no match, the address will get a distance which is further than any non-negated list element, and closer than any negated element. Because of the first-match aspect of the algorithm, an element that de- fines a subset of another element in the list should come before the broader element, regardless of whether either is negated. For example, in 1.2.3/24; !1.2.3.13 the 1.2.3.13 element is completely useless, because the algorithm will match any lookup for 1.2.3.13 to the 1.2.3/24 element. Using !1.2.3.13; 1.2.3/24 fixes that problem by having 1.2.3.13 blocked by the negation but all other 1.2.3.* hosts fall through. TTHHEE LLOOGGGGIINNGG SSTTAATTEEMMEENNTT SSyynnttaaxx logging { [ channel _c_h_a_n_n_e_l___n_a_m_e { ( file _p_a_t_h___n_a_m_e [ versions ( _n_u_m_b_e_r | unlimited ) ] [ size _s_i_z_e___s_p_e_c ] | syslog ( kern | user | mail | daemon | auth | syslog | lpr | news | uucp | cron | authpriv | ftp | local0 | local1 | local2 | local3 | local4 | local5 | local6 | local7 ) | null ); [ severity ( critical | error | warning | notice | info | debug [ _l_e_v_e_l ] | dynamic ); ] [ print-category _y_e_s___o_r___n_o; ] [ print-severity _y_e_s___o_r___n_o; ] [ print-time _y_e_s___o_r___n_o; ] }; ] [ category _c_a_t_e_g_o_r_y___n_a_m_e { _c_h_a_n_n_e_l___n_a_m_e; [ _c_h_a_n_n_e_l___n_a_m_e; ... ] }; ] ... }; DDeeffiinniittiioonn aanndd UUssaaggee The llooggggiinngg statement configures a wide variety of logging options for the nameserver. Its cchhaannnneell phrase associates output methods, format op- tions and severity levels with a name that can then be used with the ccaatteeggoorryy phrase to select how various classes of messages are logged. Only one llooggggiinngg statement is used to define as many channels and cate- gories as are wanted. If there are multiple logging statements in a con- figuration, the first defined determines the logging, and warnings are issued for the others. If there is no logging statement, the logging configuration will be: logging { category default { default_syslog; default_debug; }; category panic { default_syslog; default_stderr; }; category packet { default_debug; }; category eventlib { default_debug; }; }; The logging configuration is established as soon as the llooggggiinngg statement is parsed. If you want to redirect messages about processing of the en- tire configuration file, the llooggggiinngg statement must appear first. Even if you do not redirect configuration file parsing messages, we recommend always putting the llooggggiinngg statement first so that this rule need not be consciously recalled if you ever do need want the parser's messages relo- cated. TThhee cchhaannnneell pphhrraassee All log output goes to one or more ``channels''; you can make as many of them as you want. Every channel definition must include a clause that says whether messages selected for the channel go to a file, to a particular syslog facility, or are discarded. It can optionally also limit the message severity lev- el that will be accepted by the channel (default is info), and whether to include a time stamp generated by nnaammeedd, the category name, or severity level. The default is not to include any of those three. The word null as the destination option for the channel will cause all messages sent to it to be discarded; other options for the channel are meaningless. The ffiillee clause can include limitations both on how large the file is al- lowed to become, and how many versions of the file will be saved each time the file is opened. The ssiizzee option for files is simply a hard ceiling on log growth. If the file ever exceeds the size, then nnaammeedd will just not write anything more to it until the file is reopened; exceeding the size does not automati- cally trigger a reopen. The default behavior is to not limit the size of the file. If you use the vveerrssiioonn logfile option, then nnaammeedd will retain that many backup versions of the file by renaming them when opening. For example, if you choose to keep 3 old versions of the file lamers.log then just be- fore it is opened lamers.log.1 is renamed to lames.log.2, lamers.log.0 is renamed to lamers.log.1, and lamers.log is renamed to lamers.log.0. No rolled versions are kept by default; any existing log file is simply ap- pended. The unlimited keyword is synonymous with 99 in current BIND re- leases. Example usage of size and versions options: channel an_example_level { file "lamers.log" versions 3 size 20m; print-time yes; print-category yes; }; The argument for the ssyysslloogg clause is a syslog facility as described in the syslog(3) manual page. How ssyyssllooggdd will handle messages sent to this facility is described in the syslog.conf(5) manual page. If you have a system which uses a very old version of syslog that only uses two argu- ments to the ooppeennlloogg(())() function, then this clause is silently ignored. The sseevveerriittyy clause works like syslog's ``priorities'', except that they can also be used if you are writing straight to a file rather than using syslog. Messages which are not at least of the severity level given will not be selected for the channel; messages of higher severity levels will be accepted. If you are using syslog, then the _s_y_s_l_o_g_._c_o_n_f priorities will also deter- mine what eventually passes through. For example, defining a channel fa- cility and severity as daemon and debug but only logging daemon.warning via _s_y_s_l_o_g_._c_o_n_f will cause messages of severity info and notice to be dropped. If the situation were reversed, with nnaammeedd writing messages of only warning or higher, then ssyyssllooggdd would print all messages it received from the channel. The server can supply extensive debugging information when it is in de- bugging mode. If the server's global debug level is greater than zero, then debugging mode will be active. The global debug level is set either by starting the nnaammeedd server with the --dd flag followed by a positive in- teger, or by sending the running server the SIGUSR1 signal (for example, by using nnddcc ttrraaccee). The global debug level can be set to zero, and de- bugging mode turned off, by sending the server the SIGUSR2 signal (as with nnddcc nnoottrraaccee). All debugging messages in the server have a debug lev- el, and higher debug levels give more more detailed output. Channels that specify a specific debug severity, e.g. channel specific_debug_level { file "foo"; severity debug 3; }; will get debugging output of level 3 or less any time the server is in debugging mode, regardless of the global debugging level. Channels with dynamic severity use the server's global level to determine what messages to print. If pprriinntt--ttiimmee has been turned on, then the date and time will be logged. pprriinntt--ttiimmee may be specified for a syslog channel, but is usually point- less since syslog also prints the date and time. If pprriinntt--ccaatteeggoorryy is requested, then the category of the message will be logged as well. Fi- nally, if pprriinntt--sseevveerriittyy is on, then the severity level of the message will be logged. The pprriinntt-- options may be used in any combination, and will always be printed in the following order: time, category, severity. Here is an example where all three pprriinntt-- options are on: 28-Apr-1997 15:05:32.863 default: notice: Ready to answer queries. There are four predefined channels that are used for nnaammeedd ''ss default logging as follows. How they are used used is described in the next sec- tion, _T_h_e _c_a_t_e_g_o_r_y _p_h_r_a_s_e_. channel default_syslog { syslog daemon; # send to syslog's daemon facility severity info; # only send priority info and higher }; channel default_debug { file "named.run"; # write to named.run in the working directory # Note: stderr is used instead of "named.run" # if the server is started with the -f option. severity dynamic; # log at the server's current debug level }; channel default_stderr { # writes to stderr file ""; # this is illustrative only; there's currently # no way of specifying an internal file # descriptor in the configuration language. severity info; # only send priority info and higher }; channel null { null; # toss anything sent to this channel }; Once a channel is defined, it cannot be redefined. Thus you cannot alter the built-in channels directly, but you can modify the default logging by pointing categories at channels you have defined. TThhee ccaatteeggoorryy pphhrraassee There are many categories, so you can send the logs you want to see wher- ever you want, without seeing logs you don't want. If you don't specify a list of channels for a category, then log messages in that category will be sent to the default category instead. If you don't specify a de- fault category, the following ``default default'' is used: category default { default_syslog; default_debug; }; As an example, let's say you want to log security events to a file, but you also want keep the default logging behavior. You'd specify the fol- lowing: channel my_security_channel { file "my_security_file"; severity info; }; category security { my_security_channel; default_syslog; default_debug; }; To discard all messages in a category, specify the null channel: category lame-servers { null; }; category cname { null; }; The following categories are available: ddeeffaauulltt The catch-all. Many things still aren't classified into categories, and they all end up here. Also, if you don't specify any channels for a category, the default category is used instead. If you do not define the default category, the following definition is used: category default { default_syslog; default_debug; }; ccoonnffiigg High-level configuration file processing. ppaarrsseerr Low-level configuration file processing. qquueerriieess A short log message is generated for every query the server receives. llaammee--sseerrvveerrss Messages like ``Lame server on ...'' ssttaattiissttiiccss Statistics. ppaanniicc If the server has to shut itself down due to an internal problem, it will log the problem in this category as well as in the problem's na- tive category. If you do not define the panic category, the following definition is used: category panic { default_syslog; default_stderr; }; uuppddaattee Dynamic updates. nnccaacchhee Negative caching. xxffeerr--iinn Zone transfers the server is receiving. xxffeerr--oouutt Zone transfers the server is sending. ddbb All database operations. eevveennttlliibb Debugging info from the event system. Only one channel may be speci- fied for this category, and it must be a file channel. If you do not define the eventlib category, the following definition is used: category eventlib { default_debug; }; ppaacckkeett Dumps of packets received and sent. Only one channel may be specified for this category, and it must be a file channel. If you do not define the packet category, the following definition is used: category packet { default_debug; }; nnoottiiffyy The NOTIFY protocol. ccnnaammee Messages like ``... points to a CNAME''. sseeccuurriittyy Approved/unapproved requests. ooss Operating system problems. iinnssiisstt Internal consistency check failures. mmaaiinntteennaannccee Periodic maintenance events. llooaadd Zone loading messages. rreessppoonnssee--cchheecckkss Messages arising from response checking, such as ``Malformed response ...'', ``wrong ans. name ...'', ``unrelated additional info ...'', ``invalid RR type ...'', and ``bad referral ...''. TTHHEE OOPPTTIIOONNSS SSTTAATTEEMMEENNTT SSyynnttaaxx options { [ version _v_e_r_s_i_o_n___s_t_r_i_n_g; ] [ directory _p_a_t_h___n_a_m_e; ] [ named-xfer _p_a_t_h___n_a_m_e; ] [ dump-file _p_a_t_h___n_a_m_e; ] [ memstatistics-file _p_a_t_h___n_a_m_e; ] [ pid-file _p_a_t_h___n_a_m_e; ] [ statistics-file _p_a_t_h___n_a_m_e; ] [ auth-nxdomain _y_e_s___o_r___n_o; ] [ deallocate-on-exit _y_e_s___o_r___n_o; ] [ dialup _y_e_s___o_r___n_o; ] [ fake-iquery _y_e_s___o_r___n_o; ] [ fetch-glue _y_e_s___o_r___n_o; ] [ has-old-clients _y_e_s___o_r___n_o; ] [ host-statistics _y_e_s___o_r___n_o; ] [ multiple-cnames _y_e_s___o_r___n_o; ] [ notify _y_e_s___o_r___n_o; ] [ recursion _y_e_s___o_r___n_o; ] [ rfc2308-type1 _y_e_s___o_r___n_o; ] [ use-id-pool _y_e_s___o_r___n_o; ] [ treat-cr-as-space _y_e_s___o_r___n_o; ] [ also-notify _y_e_s___o_r___n_o; ] [ forward ( only | first ); ] [ forwarders { [ _i_n___a_d_d_r ; [ _i_n___a_d_d_r ; ... ] ] }; ] [ check-names ( master | slave | response ) ( warn | fail | ignore); ] [ allow-query { _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t }; ] [ allow-recursion { _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t }; ] [ allow-transfer { _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t }; ] [ blackhole { _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t }; ] [ listen-on [ port _i_p___p_o_r_t ] { _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t }; ] [ query-source [ address ( _i_p___a_d_d_r | * ) ] [ port ( _i_p___p_o_r_t | * ) ] ; ] [ lame-ttl _n_u_m_b_e_r; ] [ max-transfer-time-in _n_u_m_b_e_r; ] [ max-ncache-ttl _n_u_m_b_e_r; ] [ min-roots _n_u_m_b_e_r; ] [ serial-queries _n_u_m_b_e_r; ] [ transfer-format ( one-answer | many-answers ); ] [ transfers-in _n_u_m_b_e_r; ] [ transfers-out _n_u_m_b_e_r; ] [ transfers-per-ns _n_u_m_b_e_r; ] [ transfer-source _i_p___a_d_d_r; ] [ maintain-ixfr-base _y_e_s___o_r___n_o; ] [ max-ixfr-log-size _n_u_m_b_e_r; ] [ coresize _s_i_z_e___s_p_e_c ; ] [ datasize _s_i_z_e___s_p_e_c ; ] [ files _s_i_z_e___s_p_e_c ; ] [ stacksize _s_i_z_e___s_p_e_c ; ] [ cleaning-interval _n_u_m_b_e_r; ] [ heartbeat-interval _n_u_m_b_e_r; ] [ interface-interval _n_u_m_b_e_r; ] [ statistics-interval _n_u_m_b_e_r; ] [ topology { _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t }; ] [ sortlist { _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t_|_f_R _}_; _] _[ _r_r_s_e_t_-_o_r_d_e_r _{ _o_r_d_e_r___s_p_e_c ; [ _o_r_d_e_r___s_p_e_c ; ... [ [ }; }; DDeeffiinniittiioonn aanndd UUssaaggee The options statement sets up global options to be used by BIND. This statement may appear at only once in a configuration file; if more than one occurrence is found, the first occurrence determines the actual op- tions used, and a warning will be generated. If there is no options statement, an options block with each option set to its default will be used. PPaatthhnnaammeess vveerrssiioonn The version the server should report via the ndc command or via a query of name _v_e_r_s_i_o_n_._b_i_n_d in class chaos. The default is the real version number of ths server, but some server operators prefer the string ( ssuurreellyy yyoouu mmuusstt bbee jjookkiinngg ). ddiirreeccttoorryy The working directory of the server. Any non-absolute pathnames in the configuration file will be taken as relative to this directory. The default location for most server output files (e.g. _n_a_m_e_d_._r_u_n) is this directory. If a directory is not specified, the working directory de- faults to ., the directory from which the server was started. The di- rectory specified should be an absolute path. nnaammeedd--xxffeerr The pathname to the named-xfer program that the server uses for inbound zone transfers. If not specified, the default is system dependent (e.g. _/_u_s_r_/_s_b_i_n_/_n_a_m_e_d_-_x_f_e_r ). dduummpp--ffiillee The pathname of the file the server dumps the database to when it re- ceives SIGINT signal (as sent by nnddcc dduummppddbb ). If not specified, the default is _n_a_m_e_d___d_u_m_p_._d_b. mmeemmssttaattiissttiiccss--ffiillee The pathname of the file the server writes memory usage statistics to on exit, if ddeeaallllooccaattee--oonn--eexxiitt is yes. If not specified, the default is _n_a_m_e_d_._m_e_m_s_t_a_t_s. ppiidd--ffiillee The pathname of the file the server writes its process ID in. If not specified, the default is operating system dependent, but is usually _/_v_a_r_/_r_u_n_/_n_a_m_e_d_._p_i_d or _/_e_t_c_/_n_a_m_e_d_._p_i_d. The pid-file is used by programs like nnddcc that want to send signals to the running nameserver. ssttaattiissttiiccss--ffiillee The pathname of the file the server appends statistics to when it re- ceives SIGILL signal (from nnddcc ssttaattss). If not specified, the default is _n_a_m_e_d_._s_t_a_t_s. BBoooolleeaann OOppttiioonnss aauutthh--nnxxddoommaaiinn If yes, then the AA bit is always set on NXDOMAIN responses, even if the server is not actually authoritative. The default is yes. Do not turn off aauutthh--nnxxddoommaaiinn unless you are sure you know what you are doing, as some older software won't like it. ddeeaallllooccaattee--oonn--eexxiitt If yes, then when the server exits it will painstakingly deallocate ev- ery object it allocated, and then write a memory usage report to the mmeemmssttaattiissttiiccss--ffiillee. The default is no, because it is faster to let the operating system clean up. ddeeaallllooccaattee--oonn--eexxiitt is handy for detecting memory leaks. ddiiaalluupp If yes, then the server treats all zones as if they are doing zone transfers across a dial on demand dialup link, which can be brought up by traffic originating from this server. This has different effects according to zone type and concentrates the zone maintenance so that it all happens in a short interval, once every hheeaarrttbbeeaatt--iinntteerrvvaall and hopefully during the one call. It also suppresses some of the normal zone maintenance traffic. The default is no. The ddiiaalluupp option may al- so be specified in the zzoonnee statement, in which case it overrides the ooppttiioonnss ddiiaalluupp statement. If the zone is a mmaasstteerr then the server will send out NOTIFY request to all the slaves. This will trigger the zone up to date checking in the slave (providing it supports NOTIFY) allowing the slave to verify the zone while the call us up. If the zone is a ssllaavvee or ssttuubb then the server will suppress the zone regular zone up to date queries and only perform the when the hheeaarrttbbeeaatt--iinntteerrvvaall expires. ffaakkee--iiqquueerryy If yes, the server will simulate the obsolete DNS query type IQUERY. The default is no. ffeettcchh--gglluuee If yes (the default), the server will fetch ``glue'' resource records it doesn't have when constructing the additional data section of a re- sponse. ffeettcchh--gglluuee nnoo can be used in conjunction with rreeccuurrssiioonn nnoo to prevent the server's cache from growing or becoming corrupted (at the cost of requiring more work from the client). hhaass--oolldd--cclliieennttss Setting the option to yes, is equivalent to setting the following three options: aauutthh--nnxxddoommaaiinn yyeess ;;,, mmaaiinnttaaiinn--iixxffrr--bbaassee yyeess ;;,, and rrffcc22330088--ttyyppee11 nnoo; hhaass--oolldd--cclliieennttss with aauutthh--nnxxddoommaaiinn, mmaaiinnttaaiinn--iixxffrr-- bbaassee, and rrffcc22330088--ttyyppee11 is order dependant. hhoosstt--ssttaattiissttiiccss If yes, then statistics are kept for every host that the the nameserver interacts with. The default is no. _N_o_t_e_: turning on hhoosstt--ssttaattiissttiiccss can consume huge amounts of memory. mmaaiinnttaaiinn--iixxffrr--bbaassee If yes, statistics are kept for every host that the nameserver inter- acts with. The default is no. _N_o_t_e_: turning on host-statistics can consume huge amounts of memory. mmuullttiippllee--ccnnaammeess If yes, then multiple CNAME resource records will be allowed for a do- main name. The default is no. Allowing multiple CNAME records is against standards and is not recommended. Multiple CNAME support is available because previous versions of BIND allowed multiple CNAME records, and these records have been used for load balancing by a num- ber of sites. nnoottiiffyy If yes (the default), DNS NOTIFY messages are sent when a zone the server is authoritative for changes. The use of NOTIFY speeds conver- gence between the master and its slaves. Slave servers that receive a NOTIFY message and understand it will contact the master server for the zone and see if they need to do a zone transfer, and if they do, they will initiate it immediately. The nnoottiiffyy option may also be specified in the zzoonnee statement, in which case it overrides the ooppttiioonnss nnoottiiffyy statement. rreeccuurrssiioonn If yes, and a DNS query requests recursion, then the server will at- tempt to do all the work required to answer the query. If recursion is not on, the server will return a referral to the client if it doesn't know the answer. The default is yes. See also ffeettcchh--gglluuee above. rrffcc22330088--ttyyppee11 If yes, the server will send NS records along with the SOA record for negative answers. You need to set this to no if you have an old BIND server using you as a forwarder that does not understand negative an- swers which contain both SOA and NS records or you have an old version of sendmail. The correct fix is to upgrade the broken server or send- mail. The default is no. uussee--iidd--ppooooll If yes, the server will keep track of its own outstanding query ID's to avoid duplication and increase randomness. This will result in 128KB more memory being consumed by the server. The default is no. ttrreeaatt--ccrr--aass--ssppaaccee If yes, the server will treat CR characters the same way it treats a space or tab. This may be necessary when loading zone files on a UNIX system that were generated on an NT or DOS machine. The default is no. AAllssoo--NNoottiiffyy aallssoo--nnoottiiffyy Defines a global list of IP addresses that also get sent NOTIFY messages whenever a fresh copy of the zone is loaded. This helps to ensure that copies of the zones will quickly converge on ``stealth'' servers. If an aallssoo--nnoottiiffyy list is given in a zzoonnee statement, it will override the ooppttiioonnss aallssoo--nnoottiiffyy statement. When a zzoonnee nnoottiiffyy statement is set to nnoo, the IP addresses in the global aallssoo--nnoottiiffyy list will not get sent NOTIFY messages for that zone. The default is the empty list (no global notifi- cation list). FFoorrwwaarrddiinngg The forwarding facility can be used to create a large site-wide cache on a few servers, reducing traffic over links to external nameservers. It can also be used to allow queries by servers that do not have direct ac- cess to the Internet, but wish to look up exterior names anyway. For- warding occurs only on those queries for which the server is not authori- tative and does not have the answer in its cache. ffoorrwwaarrdd This option is only meaningful if the ffoorrwwaarrddeerrss list is not empty. A value of first, the default, causes the server to query the forwarders first, and if that doesn't answer the question the server will then look for the answer itself. If only is specified, the server will only query the forwarders. ffoorrwwaarrddeerrss Specifies the IP addresses to be used for forwarding. The default is the empty list (no forwarding). Forwarding can also be configured on a per-zone basis, allowing for the global forwarding options to be overridden in a variety of ways. You can set particular zones to use different forwarders, or have different ffoorrwwaarrdd oonnllyy//ffiirrsstt behavior, or to not forward at all. See _T_H_E _Z_O_N_E _S_T_A_T_E_M_E_N_T section for more information. Future versions of BIND 8 will provide a more powerful forwarding system. The syntax described above will continue to be supported. NNaammee CChheecckkiinngg The server can check domain names based upon their expected client con- texts. For example, a domain name used as a hostname can be checked for compliance with the RFCs defining valid hostnames. Three checking methods are available: iiggnnoorree No checking is done. wwaarrnn Names are checked against their expected client contexts. Invalid names are logged, but processing continues normally. ffaaiill Names are checked against their expected client contexts. Invalid names are logged, and the offending data is rejected. The server can check names three areas: master zone files, slave zone files, and in responses to queries the server has initiated. If cchheecckk-- nnaammeess rreessppoonnssee ffaaiill has been specified, and answering the client's ques- tion would require sending an invalid name to the client, the server will send a REFUSED response code to the client. The defaults are: check-names master fail; check-names slave warn; check-names response ignore; cchheecckk--nnaammeess may also be specified in the zzoonnee statement, in which case it overrides the ooppttiioonnss cchheecckk--nnaammeess statement. When used in a zzoonnee state- ment, the area is not specified (because it can be deduced from the zone type). AAcccceessss CCoonnttrrooll Access to the server can be restricted based on the IP address of the re- questing system or via shared secret keys. See _A_D_D_R_E_S_S _M_A_T_C_H _L_I_S_T_S for details on how to specify access criteria. aallllooww--qquueerryy Specifies which hosts are allowed to ask ordinary questions. aallllooww-- qquueerryy may also be specified in the zzoonnee statement, in which case it overrides the ooppttiioonnss aallllooww--qquueerryy statement. If not specified, the de- fault is aallllooww--rreeccuurrssiioonn Specifies which hosts are allowed to ask recursive questions. aallllooww-- rreeccuurrssiioonn may also be specified in the zzoonnee statement, in which case it overrides the ooppttiioonnss aallllooww--rreeccuurrssiioonn statement. If not speci- fied, the default is to allow recursive queries from all hosts. aallllooww--ttrraannssffeerr Specifies which hosts are allowed to receive zone transfers from the server. aallllooww--ttrraannssffeerr may also be specified in the zzoonnee statement, in which case it overrides the ooppttiioonnss aallllooww--ttrraannssffeerr statement. If not specified, the default is to allow transfers from all hosts. bbllaacckkhhoollee Specifies a list of addresses that the server will not accept queries from or use to resolve a query. Queries from these addresses will not be responded to. IInntteerrffaacceess The interfaces and ports that the server will answer queries from may be specified using the lliisstteenn--oonn option. lliisstteenn--oonn takes an optional port, and an address match list. The server will listen on all inter- faces allowed by the address match list. If a port is not specified, port 53 will be used. Multiple lliisstteenn--oonn statements are allowed. For example, listen-on { 5.6.7.8; }; listen-on port 1234 { !1.2.3.4; 1.2/16; }; will enable the nameserver on port 53 for the IP address 5.6.7.8, and on port 1234 of an address on the machine in net 1.2 that is not 1.2.3.4. If no lliisstteenn--oonn is specified, the server will listen on port 53 on all interfaces. QQuueerryy AAddddrreessss If the server doesn't know the answer to a question, it will query oth- er nameservers. qquueerryy--ssoouurrccee specifies the address and port used for such queries. If aaddddrreessss is * or is omitted, a wildcard IP address ( INADDR_ANY) will be used. If _p_o_r_t is * or is omitted, a random unpriv- ileged port will be used. The default is query-source address * port *; Note: qquueerryy--ssoouurrccee currently applies only to UDP queries; TCP queries always use a wildcard IP address and a random unprivileged port. ZZoonnee TTrraannssffeerrss mmaaxx--ttrraannssffeerr--ttiimmee--iinn Inbound zone transfers ( nnaammeedd--xxffeerr processes) running longer than this many minutes will be terminated. The default is 120 minutes (2 hours). ttrraannssffeerr--ffoorrmmaatt The server supports two zone transfer methods. one-answer uses one DNS message per resource record transferred. many-answers packs as many resource records as possible into a message. many-answers is more efficient, but is only known to be understood by BIND 8.1 and patched versions of BIND 4.9.5. The default is one-answer. ttrraannssffeerr-- ffoorrmmaatt may be overridden on a per-server basis by using the sseerrvveerr statement. ttrraannssffeerrss--iinn The maximum number of inbound zone transfers that can be running con- currently. The default value is 10. Increasing ttrraannssffeerrss--iinn may speed up the convergence of slave zones, but it also may increase the load on the local system. ttrraannssffeerrss--oouutt This option will be used in the future to limit the number of concur- rent outbound zone transfers. It is checked for syntax, but is oth- erwise ignored. ttrraannssffeerrss--ppeerr--nnss The maximum number of inbound zone transfers ( nnaammeedd--xxffeerr processes) that can be concurrently transferring from a given remote nameserver. The default value is 2. Increasing ttrraannssffeerrss--ppeerr--nnss may speed up the convergence of slave zones, but it also may increase the load on the remote nameserver. ttrraannssffeerrss--ppeerr--nnss may be overridden on a per-serv- er basis by using the ttrraannssffeerrss phrase of the sseerrvveerr statement. ttrraannssffeerr--ssoouurrccee ttrraannssffeerr--ssoouurrccee determines which local address will be bound to the TCP connection used to fetch all zones transferred inbound by the server. If not set, it defaults to a system controlled value which will usually be the address of the interface ``closest to`` the re- mote end. This address must appear in the remote end's aallllooww-- ttrraannssffeerr option for the zones being transferred, if one is specified. This statement sets the ttrraannssffeerr--ssoouurrccee for all zones, but can be overriden on a per-zone basis by includinga ttrraannssffeerr--ssoouurrccee statement within the zone block in the configuration file. RReessoouurrccee LLiimmiittss The server's usage of many system resources can be limited. Some oper- ating systems don't support some of the limits. On such systems, a warning will be issued if the unsupported limit is used. Some operat- ing systems don't support limiting resources, and on these systems a set resource limits on this system message will be logged. Scaled values are allowed when specifying resource limits. For exam- ple, 1G can be used instead of 1073741824 to specify a limit of one gi- gabyte. unlimited requests unlimited use, or the maximum available amount. default uses the limit that was in force when the server was started. See the definition of _s_i_z_e___s_p_e_c in the _D_O_C_U_M_E_N_T_A_T_I_O_N _D_E_F_I_N_I_T_I_O_N_S section for more details. ccoorreessiizzee The maximum size of a core dump. The default value is default. ddaattaassiizzee The maximum amount of data memory the server may use. The default value is default. ffiilleess The maximum number of files the server may have open concurrently. The default value is unlimited. Note that on some operating systems the server cannot set an unlimited value and cannot determine the maximum number of open files the kernel can support. On such sys- tems, choosing unlimited will cause the server to use the larger of the _r_l_i_m___m_a_x from ggeettrrlliimmiitt(_R_L_I_M_I_T___N_O_F_I_L_E) and the value returned by ssyyssccoonnff(___S_C___O_P_E_N___M_A_X). If the actual kernel limit is larger than this value, use lliimmiitt ffiilleess to specify the limit explicitly. mmaaxx--iixxffrr--lloogg--ssiizzee The max-ixfr-log-size will be used in a future release of the server to limit the size of the transaction log kept for Incremental Zone Transfer. ssttaacckkssiizzee The maximum amount of stack memory the server may use. The default value is default. PPeerriiooddiicc TTaasskk IInntteerrvvaallss cclleeaanniinngg--iinntteerrvvaall The server will remove expired resource records from the cache every cclleeaanniinngg--iinntteerrvvaall minutes. The default is 60 minutes. If set to 0, no periodic cleaning will occur. hheeaarrttbbeeaatt--iinntteerrvvaall The server will perform zone maintenance tasks for all zones marked ddiiaalluupp yyeess whenever this interval expires. The default is 60 min- utes. Reasonable values are up to 1 day (1440 minutes). If set to 0, no zone maintenance for these zones will occur. iinntteerrffaaccee--iinntteerrvvaall The server will scan the network interface list every iinntteerrffaaccee-- iinntteerrvvaall minutes. The default is 60 minutes. If set to 0, interface scanning will only occur when the configuration file is loaded. Af- ter the scan, listeners will be started on any new interfaces (pro- vided they are allowed by the lliisstteenn--oonn configuration). Listeners on interfaces that have gone away will be cleaned up. ssttaattiissttiiccss--iinntteerrvvaall Nameserver statistics will be logged every ssttaattiissttiiccss--iinntteerrvvaall min- utes. The default is 60. If set to 0, no statistics will be logged. TTooppoollooggyy All other things being equal, when the server chooses a nameserver to query from a list of nameservers, it prefers the one that is topologi- cally closest to itself. The ttooppoollooggyy statement takes an address match list and interprets it in a special way. Each top-level list element is assigned a distance. Non-negated elements get a distance based on their position in the list, where the closer the match is to the start of the list, the shorter the distance is between it and the server. A negated match will be assigned the maximum distance from the server. If there is no match, the address will get a distance which is further than any non-negated list element, and closer than any negated element. For example, topology { 10/8; !1.2.3/24; { 1.2/16; 3/8; }; }; will prefer servers on network 10 the most, followed by hosts on net- work 1.2.0.0 (netmask 255.255.0.0) and network 3, with the exception of hosts on network 1.2.3 (netmask 255.255.255.0), which is preferred least of all. The default topology is topology { localhost; localnets; }; RReessoouurrccee RReeccoorrdd ssoorrttiinngg When returning multiple RRs, the nameserver will normally return them in RRoouunndd RRoobbiinn, i.e. after each request, the first RR is put to the end of the list. As the order of RRs is not defined, this should not cause any problems. The client resolver code should re-arrange the RRs as appropriate, i.e. using any addresses on the local net in preference to other addresses. However, not all resolvers can do this, or are not correctly config- ured. When a client is using a local server, the sorting can be performed in the server, based on the client's address. This only requires configur- ing the nameservers, not all the clients. The ssoorrttlliisstt statement takes an address match list and interprets it even more specially than the statement does. Each top level statement in the sortlist must itself be an explicit ad- dress match list with one or two elements. The first element (which may be an IP address, an IP prefix, an ACL name or nested address match list) of each top level list is checked against the source address of the query until a match is found. Once the source address of the query has been matched, if the top level statement contains only one element, the actual primitive element that matched the source address is used to select the address in the re- sponse to move to the beginning of the response. If the statement is a list of two elements, the second element is treated like the address match list in a topology statement. Each top level element is assigned a distance and the address in the response with the minimum distance is moved to the beginning of the response. In the following example, any queries received from any of the address- es of the host itself will get responses preferring addresses on any of the locally connected networks. Next most preferred are addresses on the 192.168.1/24 network, and after that either the 192.168.2/24 or 192.168.3/24 network with no preference shown between these two net- works. Queries received from a host on the 192.168.1/24 network will prefer other addresses on that network to the 192.168.2/24 and 192.168.3/24 networks. Queries received from a host on the 192.168.4/24 or the 192.168.5/24 network will only prefer other addresses on their directly connected networks. sortlist { { localhost; // IF the local host { localnets; // THEN first fit on the 192.168.1/24; // following nets { 192,168.2/24; 192.168.3/24; }; }; }; { 192.168.1/24; // IF on class C 192.168.1 { 192.168.1/24; // THEN use .1, or .2 or .3 { 192.168.2/24; 192.168.3/24; }; }; }; { 192.168.2/24; // IF on class C 192.168.2 { 192.168.2/24; // THEN use .2, or .1 or .3 { 192.168.1/24; 192.168.3/24; }; }; }; { 192.168.3/24; // IF on class C 192.168.3 { 192.168.3/24; // THEN use .3, or .1 or .2 { 192.168.1/24; 192.168.2/24; }; }; }; { { 192.168.4/24; 192.168.5/24; }; // if .4 or .5, prefer that net }; }; The following example will give reasonable behaviour for the local host and hosts on directly connected networks. It is similar to the behavior of the address sort in BIND 4.9.x. Responses sent to queries from the local host will favor any of the directly connected networks. Responses sent to queries from any other hosts on a directly connected network will prefer addresses on that same network. Responses to other queries will not be sorted. sortlist { { localhost; localnets; }; { localnets; }; }; RRRRsseett OOrrddeerriinngg When multiple records are returned in an answer it may be useful to configure the order the records are placed into the response. For exam- ple the records for a zone might be configured to always be returned in the order they are defined in the zone file. Or perhaps a random shuf- fle of the records as they are returned is wanted. The rrset-order statement permits configuration of the ordering made of the records in a multiple record response. The default, if no ordering is defined, is a cyclic ordering (round robin). An oorrddeerr__ssppeecc is defined as follows: [ _c_l_a_s_s _c_l_a_s_s___n_a_m_e ][ _t_y_p_e _t_y_p_e___n_a_m_e ][ _n_a_m_e "FQDN" ] _o_r_d_e_r ordering If no class is specified, the default is AANNYY. If no Ictype is speci- fied, the default is AANNYY. If no name is specified, the default is "*". The legal values for oorrddeerriinngg are: ffiixxeedd Records are returned in the order they are defined in the zone file. rraannddoomm Records are returned in some random order. ccyycclliicc Records are returned in a round-robin order. For example: rrset-order { class IN type A name "rc.vix.com" order random; order cyclic; }; will cause any responses for type A records in class IN that have "rc.vix.com" as a suffix, to always be returned in random order. All other records are returned in cyclic order. If multiple rrrrsseett--oorrddeerr statements appear, they are not combined--the last one applies. If no rrrrsseett--oorrddeerr statement is specified, a default one of: rrset-order { class ANY type ANY name "*" order cyclic ; }; is used. TTuunniinngg llaammee--ttttll Sets the number of seconds to cache a lame server indication. 0 dis- ables caching. Default is 600 (10 minutes). Maximum value is 1800 (30 minutes) mmaaxx--nnccaacchhee--ttttll To reduce network traffic and increase performance the server store negative answers. mmaaxx--nnccaacchhee--ttttll is used to set a maximum retention time for these answers in the server is seconds. The default mmaaxx-- nnccaacchhee--ttttll is 10800 seconds (3 hours). mmaaxx--nnccaacchhee--ttttll cannot exceed the maximum retention time for ordinary (positive) answers (7 days) and will be silently truncated to 7 days if set to a value which is greater that 7 days. mmiinn--rroooottss The minimum number of root servers that is required for a request for the root servers to be accepted. Default is 2. TTHHEE ZZOONNEE SSTTAATTEEMMEENNTT SSyynnttaaxx zone _d_o_m_a_i_n___n_a_m_e [ ( in | hs | hesiod | chaos ) ] { type master; file _p_a_t_h___n_a_m_e; [ check-names ( warn | fail | ignore ); ] [ allow-update { _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t }; ] [ allow-query { _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t }; ] [ allow-transfer { _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t }; ] [ dialup _y_e_s___o_r___n_o; ] [ notify _y_e_s___o_r___n_o; ] [ also-notify { _i_p___a_d_d_r; [ _i_p___a_d_d_r; ... ] }; [ pubkey _n_u_m_b_e_r _n_u_m_b_e_r _n_u_m_b_e_r _s_t_r_i_n_g; ] }; zone _d_o_m_a_i_n___n_a_m_e [ ( in | hs | hesiod | chaos ) ] { type ( slave | stub ); [ file _p_a_t_h___n_a_m_e; ] masters [ port _i_p___p_o_r_t ] { _i_p___a_d_d_r; [ _i_p___a_d_d_r; ... ] }; [ check-names ( warn | fail | ignore ); ] [ allow-update { _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t }; ] [ allow-query { _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t }; ] [ allow-transfer { _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t }; ] [ transfer-source _i_p___a_d_d_r; ] [ max-transfer-time-in _n_u_m_b_e_r; ] [ notify _y_e_s___o_r___n_o; ] [ also-notify { _i_p___a_d_d_r; [ _i_p___a_d_d_r; ... ] }; [ pubkey _n_u_m_b_e_r _n_u_m_b_e_r _n_u_m_b_e_r _s_t_r_i_n_g; ] }; zone _d_o_m_a_i_n___n_a_m_e [ ( in | hs | hesiod | chaos ) ] { type forward; [ forward ( only | first ); ] [ forwarders { [ _i_p___a_d_d_r ; [ _i_p___a_d_d_r ; ... ] ] }; ] [ check-names ( warn | fail | ignore ); ] }; zone "." [ ( in | hs | hesiod | chaos ) ] { type hint; file _p_a_t_h___n_a_m_e; [ check-names ( warn | fail | ignore ); ] }; DDeeffiinniittiioonn aanndd UUssaaggee The zzoonnee statement is used to define how information about particular DNS zones is managed by the server. There are five different zone types. mmaasstteerr The server has a master copy of the data for the zone and will be able to provide authoritative answers for it. ssllaavvee A ssllaavvee zone is a replica of a master zone. The mmaasstteerrss list specifies one or more IP addresses that the slave contacts to update its copy of the zone. If a ppoorrtt is specified then checks to see if the zone is current and zone transfers will be done to the port given. If ffiillee is specified, then the replica will be written to the named file. Use of the ffiillee clause is highly recommended, since it often speeds server startup and eliminates a needless waste of bandwidth. ssttuubb A ssttuubb zone is like a slave zone, except that it replicates only the NS records of a master zone instead of the entire zone. ffoorrwwaarrdd A ffoorrwwaarrdd zone is used to direct all queries in it to other servers, as described in _T_H_E _O_P_T_I_O_N_S _S_T_A_T_E_M_E_N_T section. The specification of op- tions in such a zone will override any global options declared in the ooppttiioonnss statement. If either no ffoorrwwaarrddeerrss clause is present in the zone or an empty list for ffoorrwwaarrddeerrss is given, then no forwarding will be done for the zone, cancelling the effects of any ffoorrwwaarrddeerrss in the ooppttiioonnss statement. Thus if you want to use this type of zone to change only the behavior of the global ffoorrwwaarrdd option, and not the servers used, then you also need to respecify the global forwarders. hhiinntt The initial set of root nameservers is specified using a hhiinntt zone. When the server starts up, it uses the root hints to find a root name- server and get the most recent list of root nameservers. Note: previous releases of BIND used the term pprriimmaarryy for a master zone, sseeccoonnddaarryy for a slave zone, and ccaacchhee for a hint zone. CCllaasssseess The zone's name may optionally be followed by a class. If a class is not specified, class iinn (for "internet"), is assumed. This is correct for the vast majority of cases. The hheessiioodd class is for an information service from MIT's Project Athena. It is used to share information about various systems databases, such as users, groups, printers and so on. More information can be found at ftp://athena-dist.mit.edu/pub/ATHENA/usenix/athena_changes.PS. The key- word hhss is a synonym for hheessiioodd. Another MIT development was CHAOSnet, a LAN protocol created in the mid-1970s. It is still sometimes seen on LISP stations and other hard- ware in the AI community, and zone data for it can be specified with the cchhaaooss class. OOppttiioonnss cchheecckk--nnaammeess See the subsection on _N_a_m_e _C_h_e_c_k_i_n_g in _T_H_E _O_P_T_I_O_N_S _S_T_A_T_E_M_E_N_T. aallllooww--qquueerryy See the description of aallllooww--qquueerryy in the _A_c_c_e_s_s _C_o_n_t_r_o_l subsection of _T_H_E _O_P_T_I_O_N_S _S_T_A_T_E_M_E_N_T. aallllooww--uuppddaattee Specifies which hosts are allowed to submit Dynamic DNS updates to the server. The default is to deny updates from all hosts. aallllooww--ttrraannssffeerr See the description of aallllooww--ttrraannssffeerr in the _A_c_c_e_s_s _C_o_n_t_r_o_l subsection of _T_H_E _O_P_T_I_O_N_S _S_T_A_T_E_M_E_N_T. ttrraannssffeerr--ssoouurrccee ttrraannssffeerr--ssoouurrccee determines which local address will be bound to the TCP connection used to fetch this zone. If not set, it defaults to a sys- tem controlled value which will usually be the address of the interface ``closest to'' the remote end. This address must appear in the remote end's aallllooww--ttrraannssffeerr option for this zone if one is specified. mmaaxx--ttrraannssffeerr--ttiimmee--iinn See the description of mmaaxx--ttrraannssffeerr--ttiimmee--iinn in the _Z_o_n_e _T_r_a_n_s_f_e_r_s sub- section of _T_H_E _O_P_T_I_O_N_S _S_T_A_T_E_M_E_N_T. ddiiaalluupp See the description of ddiiaalluupp in the _B_o_o_l_e_a_n _O_p_t_i_o_n_s subsection of _T_H_E _O_P_T_I_O_N_S _S_T_A_T_E_M_E_N_T. nnoottiiffyy See the description of _n_o_t_i_f_y in the _B_o_o_l_e_a_n _O_p_t_i_o_n_s subsection of the _T_H_E _O_P_T_I_O_N_S _S_T_A_T_E_M_E_N_T. aallssoo--nnoottiiffyy aallssoo--nnoottiiffyy is only meaningful if nnoottiiffyy is active for this zone. The set of machines that will receive a DNS NOTIFY message for this zone is made up of all the listed nameservers for the zone (other than the pri- mary master) plus any IP addresses specified with aallssoo--nnoottiiffyy. aallssoo-- nnoottiiffyy is not meaningful for ssttuubb zones. The default is the empty list. ffoorrwwaarrdd ffoorrwwaarrdd is only meaningful if the zone has a ffoorrwwaarrddeerrss list. The oonnllyy value causes the lookup to fail after trying the ffoorrwwaarrddeerrss and getting no answer, while ffiirrsstt would allow a normal lookup to be tried. ffoorrwwaarrddeerrss The ffoorrwwaarrddeerrss option in a zone is used to override the list of global forwarders. If it is not specified in a zone of type ffoorrwwaarrdd, _n_o for- warding is done for the zone; the global options are not used. ppuubbkkeeyy The DNSSEC flags, protocol, and algorithm are specified, as well as a base-64 encoded string representing the key. TTHHEE AACCLL SSTTAATTEEMMEENNTT SSyynnttaaxx acl _n_a_m_e { _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t }; DDeeffiinniittiioonn aanndd UUssaaggee The aaccll statement creates a named address match list. It gets its name from a primary use of address match lists: Access Control Lists (ACLs). Note that an address match list's name must be defined with aaccll before it can be used elsewhere; no forward references are allowed. The following ACLs are built-in: aannyy Allows all hosts. nnoonnee Denies all hosts. llooccaallhhoosstt Allows the IP addresses of all interfaces on the system. llooccaallnneettss Allows any host on a network for which the system has an interface. TTHHEE KKEEYY SSTTAATTEEMMEENNTT SSyynnttaaxx key _k_e_y___i_d { algorithm _a_l_g_o_r_i_t_h_m___i_d; secret _s_e_c_r_e_t___s_t_r_i_n_g; }; DDeeffiinniittiioonn aanndd UUssaaggee The kkeeyy statement defines a key ID which can be used in a sseerrvveerr state- ment to associate a method of authentication with a particular name serv- er that is more rigorous than simple IP address matching. A key ID must be created with the kkeeyy statement before it can be used in a sseerrvveerr defi- nition or an address match list. The _a_l_g_o_r_i_t_h_m___i_d is a string that specifies a security/authentication al- gorithm. _s_e_c_r_e_t___s_t_r_i_n_g is the secret to be used by the algorithm, and is treated as a base-64 encoded string. It should go without saying, but probably can't, that if you have _s_e_c_r_e_t___s_t_r_i_n_g _'_s in your _n_a_m_e_d_._c_o_n_f, then it should not be readable by anyone but the superuser. TTHHEE TTRRUUSSTTEEDD--KKEEYYSS SSTTAATTEEMMEENNTT SSyynnttaaxx trusted-keys { [ _d_o_m_a_i_n___n_a_m_e _f_l_a_g_s _p_r_o_t_o_c_o_l _a_l_g_o_r_i_t_h_m _k_e_y; ] }; DDeeffiinniittiioonn aanndd UUssaaggee The ttrruusstteedd--kkeeyyss statement is for use with DNSSEC-style security, origi- nally specified in RFC 2065. DNSSEC is meant to provide three distinct services: key distribution, data origin authentication, and transaction and request authentication. A complete description of DNSSEC and its use is beyond the scope of this document, and readers interested in more in- formation should start with RFC 2065 and then continue with the Internet Drafts available at http://www.ietf.org/ids.by.wg/dnssec.html. Each trusted key is associated with a domain name. Its attributes are the non-negative integral _f_l_a_g_s, _p_r_o_t_o_c_o_l, and _a_l_g_o_r_i_t_h_m, as well as a base-64 encoded string representing the _k_e_y. Any number of trusted keys can be specified. TTHHEE SSEERRVVEERR SSTTAATTEEMMEENNTT SSyynnttaaxx server _i_p___a_d_d_r { [ bogus _y_e_s___o_r___n_o; ] [ transfers _n_u_m_b_e_r; ] [ transfer-format ( one-answer | many-answers ); ] [ keys { _k_e_y___i_d [ _k_e_y___i_d ... ] }; ] }; DDeeffiinniittiioonn aanndd UUssaaggee The server statement defines the characteristics to be associated with a remote name server. If you discover that a server is giving out bad data, marking it as bboogguuss will prevent further queries to it. The default value of bboogguuss is no. The server supports two zone transfer methods. The first, oonnee--aannsswweerr, uses one DNS message per resource record transferred. mmaannyy--aannsswweerrss packs as many resource records as possible into a message. mmaannyy--aannsswweerrss is more efficient, but is only known to be understood by BIND 8.1 and patched versions of BIND 4.9.5. You can specify which method to use for a server with the ttrraannssffeerr--ffoorrmmaatt option. If ttrraannssffeerr--ffoorrmmaatt is not specified, the ttrraannssffeerr--ffoorrmmaatt specified by the ooppttiioonnss statement will be used. The ttrraannssffeerrss will be used in a future release of the server to limit the number of concurrent in-bound zone transfers from the specified server. It is checked for syntax but is otherwise ignored. The kkeeyyss clause is used to identify a _k_e_y___i_d defined by the kkeeyy state- ment, to be used for transaction security when talking to the remote server. The kkeeyy statememnt must come before the sseerrvveerr statement that references it. The kkeeyyss statement is intended for future use by the server. It is checked for syntax but is otherwise ignored. TTHHEE CCOONNTTRROOLLSS SSTTAATTEEMMEENNTT SSyynnttaaxx controls { [ inet _i_p___a_d_d_r port _i_p___p_o_r_t allow { _a_d_d_r_e_s_s___m_a_t_c_h___l_i_s_t; }; ] [ unix _p_a_t_h___n_a_m_e perm _n_u_m_b_e_r owner _n_u_m_b_e_r group _n_u_m_b_e_r; ] }; DDeeffiinniittiioonn aanndd UUssaaggee The ccoonnttrroollss statement declares control channels to be used by system ad- ministrators to affect the operation of the local name server. These control channels are used by the nnddcc utility to send commands to and re- trieve non-DNS results from a name server. A uunniixx control channel is a FIFO in the file system, and access to it is controlled by normal file system permissions. It is created by nnaammeedd with the specified file mode bits (see chmod(1)), user and group owner. Note that, unlike cchhmmoodd, the mode bits specified for ppeerrmm will normally have a leading 0 so the number is interpreted as octal. Also note that the user and group ownership specified as oowwnneerr and ggrroouupp must be given as numbers, not names. It is recommended that the permissions be re- stricted to administrative personnel only, or else any user on the system might be able to manage the local name server. An iinneett control channel is a TCP/IP socket accessible to the Internet, created at the specified _i_p___p_o_r_t on the specified _i_p___a_d_d_r. Modern tteellnneett clients are capable of speaking directly to these sockets, and the con- trol protocol is ARPAnet-style text. It is recommended that 127.0.0.1 be the only _i_p___a_d_d_r used, and this only if you trust all non-privileged users on the local host to manage your name server. TTHHEE IINNCCLLUUDDEE SSTTAATTEEMMEENNTT SSyynnttaaxx include _p_a_t_h___n_a_m_e; DDeeffiinniittiioonn aanndd UUssaaggee The iinncclluuddee statement inserts the specified file at the point that the iinncclluuddee statement is encountered. It cannot be used within another statement, though, so a line such as acl internal_hosts { include internal_hosts.acl; }; is not allowed. Use iinncclluuddee to break the configuration up into easily-managed chunks. For example: include "/etc/security/keys.bind"; include "/etc/acls.bind"; could be used at the top of a BIND configuration file in order to include any ACL or key information. Be careful not to type ``#include'', like you would in a C program, be- cause ``#'' is used to start a comment. EEXXAAMMPPLLEESS The simplest configuration file that is still realistically useful is one which simply defines a hint zone that has a full path to the root servers file. zone "." in { type hint; file "/var/named/root.cache"; }; Here's a more typical real-world example. /* * A simple BIND 8 configuration */ logging { category lame-servers { null; }; category cname { null; }; }; options { directory "/var/named"; }; controls { inet * port 52 allow { any; }; // a bad idea unix "/var/run/ndc" perm 0600 owner 0 group 0; // the default }; zone "isc.org" in { type master; file "master/isc.org"; }; zone "vix.com" in { type slave; file "slave/vix.com"; masters { 10.0.0.53; }; }; zone "0.0.127.in-addr.arpa" in { type master; file "master/127.0.0"; }; zone "." in { type hint; file "root.cache"; }; FFIILLEESS /etc/named.conf The BIND 8 nnaammeedd configuration file. SSEEEE AALLSSOO named(8), ndc(8) 4th Berkeley Distribution January 7, 1999 28